Piston



Mm'ch 5,1946. C.. s. CLARK 2,395,847

PISTON Filed Nov. 1, 1940 i, um v -ATToRNEY threaded to receive a chuck for holding the pis-l From the inner central part of the head portonwhile the same is being machined. l tion I 2 extends a preferably uniformly cylindrical Otherobjects and advantages of the invention, columnv I1, desirably coaxial with the outer surrelating to the particular arrangement and con- 40 face of the piston, terminatingr in hollow enstruction of the various parts, will become aplargements I8 and I9, providing bearings for theV` parent as the description proceeds. wrist pin 20, which serves for movably securing Referring to the drawing: the associated connecting rod 2| thereto. TheV Patented Mar. 5, 194e Y :1: -s a Y V Y 2,395,847@r I UNITED STATES PATENT `FFICE Y 2,395,847

PISTON Cornelius S. Clark, Norfolk, Va. vApplication November 1, 1940, Serial No. 363,855

5 claims.' (o1. 309-4) This invention relates to pistons, and more par- Figures 5, 6' andy 7 are views corresponding, re-v ticularly to such in which the wrist pin bearings spectively, to Figures 1, 2 and 3, but showing anextend from the heads, rather than from the other embodimentof my invention.

skirts, thereof. One ofthe major problems met in the construc- The principal object of my invention, generally 5 tion of pistons for internal combustion engines, considered, is to provide a piston of improved dehas been the unevenness of the expansion of the sign and in which the skirt is relatively free from piston due to variation in the thickness of secthe wrist pin bearings, whereby it may exp-and tions. Some of this variation is occasioned by and contract more uniformly than in the conthe fact that, in thepresent designs of such pisventional construction. i l0 tons, the wrist pinV bearings are'cast into and Another object of my invention is to .provide made integral with the piston skirt. AThe incor- Y a cast piston in which the bearings for the wrist poration of such masses of metal has meant that pin, or means for movably securing the connectheat is transferred to and from the thinner secing rod thereto, extend directly from the head, tions more rapidly than to and from the heavier rather than the skirt, thereof. sections, with a consequent warping of the struc- A further object of my invention is the proture. vision of a piston with a sealing strip adjacent In accordance with my improved design, as ilthe outer surface of its head, said strip being lustrated in detail in the drawingI have suceither crimped in the groove for receiving piston ceeded in eliminating this cause of uneven exring means, so that it preferably denes one side pansion and contraction by avoiding any direct wall of said groove or clamped between the head connection between the Ywrist pin bearings and and skirt portions of said piston, if the latter is the skirt, and instead carrying said'bearings diformed in two parts. rectly from the head of the piston.

A stil] further object of my invention is the In the drawing, the reference character II desprovision of a piston having a sealing strip in a ignates a pistn, embodying my invention, comgroove for receiving piston ring means, that porprising a relatively thick cylindrical head portion of said piston forming the wall of said groove, tion I 2, formed with a single peripheral groove toward the outer surface of the piston head, being I3 for receiving pistonY ring means, which may beveled in order to allow pressureefrom the cylbe one or two rings I4, Although this is all that inder and/or combustion chamber to act on said is needed in this type of piston to insure tightstrip and press it against the piston ring, thereby ness, it will be understood that more grooves preventing escape of pressure behind the ring. and rings may be used, if desired, as with con- An additional object of my invention is the ventional pistons. A .skirt portion vI5 extends provision of a piston, comprising head and skirt from the peripheral portion of the head I2 at the portions, said head portionl carrying the wrist 35 side of the grooved portion opposite to the outer pin bearings, cored for lightness, and desirably or upper surface IE of the head portion.

Figure 1 is an axial sectional View of a piston column I1 is desirably cored or bored hollow for embodying my invention, portions of the associlightness and threaded, as indicated at 22 for' ated piston rings, cylinder, cylinder head, wrist connection with a chuck for holding it while being pin, and connecting rod being also shown. machined. ,Y Y

Figure 2 is a plan View of the head end of the In order to provide for entiy of the wrist pin piston. 20, the skirt portion I5, which is thin and other- Figure 3 is an enlarged, sectional View, corre- `50 Wise continuous and uniform in thickness, is spending to the upper right hand corner of the ,apertured, as indicated at 23 and 24. However, piston sectionshown in Figure 1. one or both of these apertures may, if desired,

Figure 4 is an elevational view of one of the be ysubsequently closed by thimble bushingsV 25 thimble bushings which serve as wrist pin re-` v held in place in anyv desired manner, as by beingl tainersl, f Y Y 65 tightly ,ltted in the associated bearings I 8 .and

tioned near the free or lower edge portion thereof, rather than in a position corresponding with the location of the wrist vided between said groove and the inner surface of the piston skirt, as in the preceding 'embodiment.

The outer part of the head member 52 is desirably beveled, as indicated at 69, to allow pressure from the outer portion of the cylinder adjacent the cylinder head, to force a :dat flexible sealing ring or annular member 'H into tight sealing engagementI with the ring means. The ring 1| is desirably formed of an alloy, such as stainless steel, copper, brass or the like, and conveniently tightly clamped between the head and skirt members of the piston when assembled, thereby gripping it in place so that it functions in a manner similar to that of the sealing member 3|' of the preceding embodiment, as well as protecting the engaged wall of the ring groove against the battering action of the piston ring during the suction stroke, especially if said wall is formed of light metal or not as durable as iron or steel. A hole 'I2 is desirably provided in the skirt portion 53 to receive a spanner for tightening it against the head portion 52.

Although preferred embodiments of my invention have been disclosed, it will be understood that modications may be made within the spirit and scope of the appended claims.

I claim:

1. A piston with a peripheral groove, an expanding piston ring in said groove, and a iiat annuuar thin ilexible metal sealing member disposed between that adjacent portion of said piston dening said groove, the inner peripheral edge of said sealing member being gripped in place with respect to said piston, said sealing member being so ex-ible that when subjected to such pressure the outer pin. Holes 'l0 may be p-roportion engages the adjacent surface of said ring over a substantial area and exure takes place between the gripped and the outer portions.

2. A piston with a peripheral groove, an expanding piston ring in said` groove, and a fiat annular thin ilexible metal sealing member disposed between that side of said ring which in operation is exposed to iiuid pressure and the adjacent portion of said piston dening said groove, the inner peripheral edge of said sealing member extending beyond the bottom of said groove and gripped in place with respect to said piston, said metal selected from it overlies and forms sealing member being so nexible that when subjected to such pressure the outer portion engages the adjacent surface of said ring over a substantial area and ilexure takes place between the gripped and the outer portions.

3. A piston comprising separable portions defining a peripheral groove, an expanding piston ring in said groove, and a Iiat annular thin iiexible metal sealing member disposed between that side of said ring which in operation is exposedto fluid pressure and the adjacent portion of said piston denng said groove, the inner peripheral edge of said sealingr member being gripped in place between said separable portions, said sealing member being so exible that when subjected to such pressure flexure takes place between the gripped and the outer portions and the outer portion engages the adjacent surface of said ring over a substantial area.

4. A piston with a peripheral groove, a resiliently expansible piston ring in said groove, and a at annularthin flexible sealing member disposed between that side of said ring which in operation is exposed to fluid pressure and the adjacent portion of said piston the inner peripheral edge of said sealing member being grippingly received in a correspondingly thin groove extending from the pressure side of said ringgroove, said sealing member being` so ilexible that when subjected to said 'pressure flexure takes place between the gripped and the outer portions and the outer portion engages the adjacent surface of said ring over a substantial area.

5. A piston formed at least in part of light the group consisting of aluminum, magnesium and light alloys, and having a peripheral groove, an expanding piston ring in said groove, and a iiat annular thin exible metal sealing member disposed between thathside of said ring which in operation is exposed to fluid pressure and a light metal surface of said piston defining said groove, which light metal surface a durable shield therefor directly engaged by said ring, the inner peripheral edge of said sealing member being gripped in place with respect to said piston, said sealing member being so flexible that when` subjected to pressure during a power stroke the outer portion flexes with respect to the gripped portion and engages the adjacent surface of said ring over a substantial area.

CORNELIUS S. CLARK.

dening said groove, 

